I have a 1970 cutlass S. My tail lights and brake lights wont work. Head lights and front side lights work. Were should I start?

 

Welcome to the site, I'd start at the fuse panel.

 

push and pull the hazard light switch on the column a few times, sometimes that gets funky tail light problems cleared up.


I assume you have checked the bulbs and tail light sockets for corrosion? Are they well grounded? A jumper wire from the socket housing to a good ground would be a good test.

Check the taillight and stop lamp fuse, since you said the front lamps work, I’d assume the tail light fuse is good. Check for power at the orange wire on the brake switch, if power is there, check for power on the white wire with the brake pedal pressed. If you have power there, check for power at the green and yellow wires of the turn signal switch, with the brake pedal pressed. If that’s good, then the problem is most likely in the tail light harness. Make sure the tail light harness connector is fully seated. I’m pretty sure there is also another connector in the trunk, along with a main ground wire near the trunk latch.